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The nuclear underpinnings of Cosmogenic Nuclides

The nuclear underpinnings of Cosmogenic Nuclides. David Argento. Outline. Atomic and particle basics Atomic structure Major groups of subatomic particles Nuclear forces, structures and processes Four primary forces Radioactivity Forms of radiation. Before we launch. David Argento

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The nuclear underpinnings of Cosmogenic Nuclides

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  1. The nuclear underpinnings of Cosmogenic Nuclides David Argento

  2. Outline • Atomic and particle basics • Atomic structure • Major groups of subatomic particles • Nuclear forces, structures and processes • Four primary forces • Radioactivity • Forms of radiation

  3. Before we launch • David Argento • Graduate student • JHN423 • dargento@u.washington.edu • References • Hyperphysics: http://hyperphysics.phy-astr.gsu.edu/hbase/HFrame.html • Wickipedia: useful, but be very skeptical • Hundreds of papers • Apologies for errors, omissions, over simplicity, over complication, and pace.

  4. The Atom electron electron proton neutron

  5. Quarks

  6. Subatomic Particle Families & Generations

  7. Back to the nucleus • What happens with similar charged objects? 10-15m 10-10m FE = ~100N FG = ~10-35N

  8. Forces

  9. Nuclear Stability • The nucleus is stable in specific proton and neutron combinations • Stability is based on electric-nuclear force balance • Unstable nuclei will decay to achieve stability • Eject energy, electrical charge and nucleons (protons and neutrons) • Thus…

  10. Radioactivity • Neutrons • Neutrinos • Fission • Gamma radiation • Electromagnetic radiation • Alpha radiation • Helium nucleus • Beta radiation • Electron or positron

  11. Gamma Radiation • Electromagnetic Radiation

  12. Alpha radiation • Energetic ejection of helium-4 in 2+ state (no electrons)

  13. Beta Radiation • Energetic ejection of electron or positron

  14. Neutrons • Ejection of neutrons (low to high energy) • Can also accompany other decay modes

  15. Neutrinos • Weakly interacting, extremely small mass, and accompanies most, radioactive decay • Not important for this the purpose of this class, but there is promise for use as probe of the interior of the earth (McDonough, W. F., Mapping the interior of the Earth, Science, 31, August 2007, pp1177 - 1178)

  16. Fission • Not important for this class, but an important aspect of radioactive decay • In-situ neutron source, must be corrected for if fissile material is present

  17. Probability and the Half life • Each and every atom of an isotopic species has the same probability of decaying during a period of time. • This results in a set fraction of the population decaying in the same time period, regardless of total population • Each isotope is different

  18. Decay Curve

  19. Modeling exponential decay

  20. Population change • Take the derivative:

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